Goofs

When in the ancient city ruins, Penny loses Debbie the Bloop but when they get back to the chariot, Debbie has reappeared.

Alpha Centauri is described as a planet when in fact it is a star (actually three stars in a single star system). This mistake was later corrected.

Time values for the space journey conflict. Alpha Centauri is 4 light years from Earth (4.37 to be precise). The Gemini 12 spacecraft (renamed Jupiter 2 in the televised series) will travel there at the speed of light, taking "a century" rather than 4 years (or 4.37 years). The trip is also referred to as taking 98 years. Finally, during the meteor storm the ship is said to be moving at 18,400 miles per hour which is far less than the speed of light (186,0000 miles per second).

The spacecraft is shown going through an asteroid field, with the rocks bouncing off the craft and flying away aft of the ship. Newtonian mechanics would have the rocks flying off in the direction they were redirected after the hit, not falling off to the rear of the ship. This indicates that the model of the ship was placed in a vertical mount and the rocks were dropped onto the model in a gravity field.

The announcer at the beginning states that probes into other galaxies have identified Alpha Centauri as the one planet in range that would furnish ideal conditions for humans to live. However, Alpha Centauri is not only in our own galaxy rather than another galaxy, but its system is the closest to ours.

Although the suspended animation tubes would protect them from aging, the bodies are simply standing and not supported, so they would bounce around inside due to forces on the spacecraft such as launch and abrupt moves, as in the asteroid hits.

The ship was launched Oct. 1997, and the date in the journal after the crash was Dec. 2001 which is 4 years and 2 months, yet the journal, citing the atomic clock, reads that it was "three and a half years" since launch (that is, in "suspended animation").

This is not a goof as it is mentioned that they have been on the planet for six months. When you add in the roughly three and a half years to that, you get the 4 years difference.

John and Don visit the meteorological station bundled in parkas and talk about the cold dropping to -150 degrees by the morning, but they are clearly sweating in all their close-ups. Meanwhile, everyone else is at base camp in shirt sleeves, including Will who joins up with the men.

The enormous footprints, which alert John and Don to the presence of the cyclops, in no way match the giant's actual feet.

The spaceship, especially viewed from the exterior, is much too small to have held all of the various rooms. There is no indication of bedrooms, a garage for the Rover and a lower level where the robot is held. Mrs. Robinson does the cooking and washing outside - so there are apparently no laundry facility, bathrooms or a kitchen on board.

While running back into the cave, John pushes off a rock which flexes under him.

Penny runs off with Debbie the Bloop and is only gone for a very short time, but John flies several miles to find her. She could not have traveled that far in the time allowed on the back of a tortoise.

Will runs off with a laser gun to where John and Don are located. They are some distance away where it is much colder, but Will runs that distance in a few minutes and without a coat.

Although set 30 years in the future from the air date, there is no futuristic common tools shown. Television cameras are huge and bulky, with awkward cables to them. Telephones are all standard landline systems. Bulky film cameras are shown. Computer systems are all late '50s/early '60s design. Nothing is changed to visualize the imagined future such as display screens, wireless connections, and compact electronic items.

The TV announcer states that the family is the first of maybe as many as 10 million families a year traveling to Alpha Centauri to colonize due to the overcrowding of Earth. The trip will take the Robinsons about 98 years. However, no following families will know if it is safe to go to colonize until the Robinsons reach the planet so it will be about 100 years before the next group could leave. In 100 years, the overcrowding could have wiped out the planet or other means of dealing could have occurred. And once the Robinsons have sent communications that others should follow, it would be 100 years before anyone gets there. The Robinsons will long be dead by that time. The only ones who could be alive would be Don and Judy's children. the other option is after finding the planet safe, they all return to suspended animation to await the arrive of other colonists.

Don falls off the top of the crawler vehicle during the storm at sea and holds on to the side railings. Other members of the crew look at the roof and determine he is lost. The vehicle is surrounded by clear glass/plastic yet no one could see Don hanging onto the side of the vehicle.